I have recently enabled "Allow users to Sign in using Google" in our FD portal.
When a subset of customers that run google apps for education get to our login page and select the "or login using Google" shortcut, they receive a "OpenID auth request contains an unregistered domain: http://cclt.freshdesk.com.
We manage this customer's google services and have enabled OpenID in their domain at the following location
Go to Manage this domain. -->> Advanced tools -->> Federated Login using OpenID
I have read this article but it does not describe was is necessary to register our domain for the above functionality.